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The previous highest reading around that tank was 1,800 millisieverts on Saturday

Those levels are strong enough to kill an unprotected person within hours

Radiation readings near tanks holding toxic water at Japan's crippled nuclear power plant have jumped to a new high, the plant operator said Wednesday.

Tokyo Electric Power Company, which has been struggling to deal with a series of leaks at the Fukushima Daiichi nuclear plant, said it detected a radiation level of 2,200 millisieverts near the tanks on Tuesday. That's up from a previous high of 1,800 millisieverts on Saturday.

Those levels, detected around the same tank, are strong enough to kill an unprotected person within hours. But TEPCO said the type of radiation is easy to shield against.

The announcement of the increased reading came a day after the Japanese government officially stepped into the effort to deal with the contaminated water crisis at the Fukushima plant, which was severely damaged by the massive earthquake and tsunami that struck northeast Japan in March 2011.

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The government said Tuesday that it would spend the equivalent of $470 million on measures that included an ambitious plan to freeze the ground surrounding the plant's stricken reactors to prevent the contamination of groundwater at the site.

TEPCO has accumulated a vast volume of tainted water in roughly 1,000 huge storage tanks at the site, some of them hastily assembled in the aftermath of the tsunami.

And the amount of radioactive water at the plant keeps growing day by day, as groundwater seeps in and the company pumps liquid around the damaged reactors to keep them cool.

Last month, TEPCO said one of the tanks at the site had leaked 300 tons of toxic water, prompting Japan's nuclear regulator to declare the situation a Level 3 serious incident, its gravest assessment since the reactor meltdowns at the plant in 2011.